Gas turbine assemblies commonly comprise a plurality of turbine and compressor blades, each of which is joined to a disk through the engagement of a fir tree or dove tail blade root in a corresponding disk slot and extends radially outward from the periphery of the disk, across the path of working medium gases flowing through the engine. Due to the advent of high performance engines, and particularly in light of the concern for fuel conservation, there has been an increasing desire to avoid air leakages within the engine. Obviously, any leakage constitutes a loss of energy, efficiency, and fuel economy. This invention relates to the sealing of the gap between the blade root of each rotor blade and the slot in which it is mounted in the disk.
In the past, attempts to reduce this source of leakage have included sealant materials such as silicon rubber compositions, which are temperature limited, and epoxy cements. These solutions have had problems of maintainability and blade removal, since removal of such materials or their residues is a labor intensive and difficult process. Other approaches to the reduction of leakage between blade root and disk have included providing sealing means at the disk surface, which also provide means to lock the blade root in position in the disk. An example of such a bladed rotor assembly is shown in U.S. Pat. No. 3,807,898, of Guy et al. In this assembly, a plurality of sealing plates extend from the rotor disk to each rotor blade platform, to lock the blades in place and to block leakage between the platforms and the disk. Another locking device is illustrated in commonly owned U.S. Pat. Nos. 4,389,161 and 4,444,544, of Brumen and Rowley, respectively, which are incorporated herein by reference. According to these references, each rotor blade is retained against fore and aft movement by a lock pin, which also serves to block the leakage of working medium gases through the blade attachment slot across the disk. The present invention is particularly advantageous in conjunction with locking means such as taught by these references.